Does PKGBUILD have a syntax associated with it on arch? It seems that by default with no ,nanorc or flags nano does not have issues with this filename. I'm guessing there probably is a bug but it's in the nanorc or syntax code.

If you could include the nanorc and any syntax highlighting rules associated with the PKGBUILD file that would be helpful.

When trying to open a file with the name "PKGBUILD", nano stalls at a blank ncurses screen. Any other name works, even just a single lower case name such as "PKGbUILD". The file does not need to exist, can be an empty file, or one downloaded.. all fail.

I also tried download the current stable and compiling to make sure it was not Arch's build, but even that fails in the same way.